Bubble-free and pressure-generating electrodes for electrophoretic and electroosmotic devices

ABSTRACT

Bubble-free electrodes, electrochemical cells including bubble-free electrodes, analytical devices, and methods for preparing and using them are provided. The analytical devices each include at least one bubble-free electrode. Analytical devices that include an electrochemical cell and a sample containment device are also provided, wherein the electrochemical cell includes an anodic reservoir, a cathodic reservoir, an electrical connection between the anodic reservoir and the cathodic reservoir, and a first bubble-free electrode disposed within one of the anodic reservoir and the cathodic reservoir. A second electrode is disposed within the other reservoir and a power source is provided having a positive terminal that is normally in electrical contact with the first electrode, and a negative terminal that is normally in electrical contact with the second electrode. The analytical device further includes a power source polarity-inverting device for switching the contacts between the terminals of the power source and the first and second electrodes. The sample containment device includes a sample containment chamber having an opening for introducing a sample into the chamber and being positioned with respect to the electrochemical cell such that an electrical field generated by the electrochemical cell can influence a property of a component of a sample disposed in the sample containment chamber. Pressure-generating cells are also provided.

BACKGROUND OF THE INVENTION

[0001] For many applications regarding the generation of an electricfield in an aqueous medium, electrodes are typically placed directly inan aqueous buffer solution and connected to an external power source toform an applied voltage difference. If the applied voltage exceeds aboutone volt, as is typical in electrophoretic and electroosmoticapplications, the applied voltage causes electrolysis of water. Theelectrolysis results in the generation of hydrogen gas at the cathode(negative electrode) and oxygen gas at the anode (positive electrode).

[0002] Problems exist in operating microchannel devices and otherintegrated devices for sequencing or concentrating biomolecules becauseof the need for a connection to an external source of current, usually ahigh-voltage power supply. Conventionally, such connections are made bydipping a wire, such as a platinum wire, in small containers filled withan electrolyte buffer solution. Generated hydrogen gas bubbles andoxygen gas bubbles resulting from electrolysis are vented or escape tothe atmosphere.

[0003] In many devices that include an electrochemical cell, theformation of bubbles at one or both electrode surfaces can createserious problems. These devices include microbiological analyticaldevices, microelectrophoretic devices, bulk flow transport systems, anddevices where electrodes must be placed in confined or sealed fluidicchannels. Interfacing of such devices with the electrodes createsparticular problems. Among these problems are siphoning, evaporation ofelectrolyte, excessive current path lengths and associated heatingrequirements, excessively complex electromechanical systems andconfigurations, excessively large systems and electrolyte reservoirs,excessive reagent and/or electrolyte consumption, and in some cases theimpossibility of placing electrodes driven by DC or low frequency ACcurrent inside channels or closed chambers.

[0004] Palladium has been used as an electrode material inelectrophoretic devices, for example, the electrophoretic devicesdescribed in U.S. Pat. No. 5,833,826, which is incorporated herein inits entirety by reference. In addition, it is well known that palladiumabsorbs hydrogen. However, palladium does not absorb oxygen gasgenerated at the positive electrode of an electrochemical cell renderingit undesirable as an electrode material in microbiological analyticaldevices, microelectrophoretic devices, bulk flow transport systems, anddevices where electrodes must be placed in confined or sealed fluidicchannels.

SUMMARY OF THE INVENTION

[0005] The present invention overcomes problems associated withelectrodes that produce bubbles by providing a bubble-free electrodematerial and systems and methods employing its use. The devices of thepresent invention include one or more bubble-free electrodes, methods ofpreparing bubble-free electrodes, and analytical methods that employdevices including bubble-free electrodes. Herein, the phrase“bubble-free electrode” encompasses different electrodes that produce nobubbles during operation as defined herein.

[0006] According to an embodiment of the present invention, bubble-freepalladium electrodes prepared according to the invention are providedthat produce less bubbles than similarly dimensioned palladiumelectrodes not prepared according to the invention under similarenvironmental and electrical conditions.

[0007] According to an embodiment of the present invention, bubble-freepalladium electrodes prepared according to the invention are providedthat produce less bubbles than similarly dimensioned platinum electrodesnot prepared according to the invention under similar environmental andelectrical conditions.

[0008] According to yet another embodiment of the present invention,bubble-free anodes are provided that do not generate an oxygen bubblevisible to the naked eye when charged at a current density of about 72A/m² (amperes per square meter) for about 1.0 second in a degassedelectrolytic solution under conditions of ready-nucleation, that is,under conditions where spontaneous bubble formation preventssupersaturation of dissolved oxygen.

[0009] According to yet another embodiment of the present invention, apalladium anode is provided that includes hydrogen stored in the anodematerial in an amount sufficient to reduce the formation of oxygen gasbubbles by the anode under electrolytic conditions when compared to acomparably dimensioned palladium electrode not including the storedhydrogen.

[0010] According to an embodiment of the present invention, anelectrochemical cell is provided that includes one or more palladiumanodes that has been pre-charged as a cathode to absorb and storehydrogen within the electrode structure. Subsequently the electrode isused as an anode under electrolytic conditions to operate bubble-free.In an exemplary embodiment of the present, an electrochemical cell isprovided that includes a palladium-containing electrode that operates asan anode under normal operation of the cell, but that has beenpre-charged under conditions as a cathode. During pre-charging, hydrogengenerated at the cathode is absorbed and stored in the structure of thecathode. When the electrode is charged under reverse-electrical polarityconditions, the palladium metal material absorbs and accumulateshydrogen. After an amount of time has elapsed under the respectivereversed electrical conditions, a sufficient amount of hydrogen isabsorbed to enable the electrode to operate under normal operation as abubble-free anode. The electrode can be pre-charged for a predeterminedtime under the respective electrical conditions such that undersubsequent normal operating conditions, the electrode operates as abubble-free anode.

[0011] The present invention also provides electrochemical cells thatinclude other hydrogen-absorbing materials as cell electrode materials,particularly as materials for electrodes that normally operate as anodesunder normal operation of the cell. To accomplish storage of hydrogen inpalladium and other hydrogen-absorbing materials, an electrode of thematerial can be run under cathodic conditions prior to being used as ananode. An electrochemical cell including a switch is provided accordingto an embodiment of the present invention whereby the polarity of theelectrochemical cell can be reversed to enable the cell to run underreverse or pre-charging operation.

[0012] Whether a switch is provided or the cell is otherwise temporarilycaused to operate under pre-charging conditions of reverse polarity,pre-charging can be accomplished to an extent or for an amount of timesufficient to enable the electrode to then operate under anodicconditions as a bubble-free electrode.

[0013] According to an embodiment of the present invention, a device foraffecting one or more properties of a component in a sample is providedthat includes a bubble-free electrode. The device can include apalladium electrode as the bubble-free electrode, or some otherelectrode material or combination of materials.

[0014] Methods of generating an electrical field with one or more of theanodes and bubble-free electrodes of the present invention are alsoprovided as are methods of separating components in a sample by exposingthe components to a field generated by one or more anodes or bubble-freeelectrodes of the present invention.

[0015] According to embodiments of the present invention, methods arealso provided wherein an electrochemical cell including a bubble-freeelectrode is used to generate a field in a device, wherein the field isuseful to affect one or more properties of a component of a sample. Forexample, devices are provided according to the present invention whereina bubble-free electrode is employed to generate a field that is used toaffect the mobility of one or more components of a sample, for instance,to cause separation of sample components.

[0016] Other embodiments of the present invention include microchipdevices including pressure generators configured with frangible ormeltable seals and electronics to accomplish precise sample injectionand separation of nanoliter-sized samples.

[0017] All patents and publications mentioned herein are incorporatedherein in their entireties by reference.

[0018] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are only intended to provide a further explanationof the present invention, as claimed. The accompanying drawings, whichare incorporated in and constitute a part of this application,illustrate several exemplary embodiments of the present invention, and,together with description, serve to explain the principles of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention may be more fully understood with referenceto the accompanying figures. The figures are intended to illustrateexemplary embodiments of the present invention without limiting thescope of the invention.

[0020]FIG. 1 is a schematic view of an example of an analytical deviceaccording to an embodiment of the present invention;

[0021]FIG. 2a is a top view of an analytical device according to anembodiment of the present invention;

[0022]FIG. 2b is a cross-sectional view taken along line IIb of FIG. 2a;

[0023]FIG. 3 is a schematic view of an analytical device according toanother embodiment of the present invention;

[0024]FIG. 4 is a schematic view of an analytical device according toyet another embodiment of the present invention;

[0025]FIG. 5 is a top view of a card-type device according to anexemplary embodiment of the present invention;

[0026]FIG. 6 is a side view of a matrix device according to an exemplaryembodiment of the present invention;

[0027]FIG. 7a is a side view of a closed capillary tube analyticaldevice according to an exemplary embodiment of the present invention;

[0028]FIG. 7b is a top view of a sealing device for sealing the ends ofa plurality of capillary tubes, such as the tubes depicted in FIG. 7a;

[0029]FIG. 8a is a side view of a low frequency concentrator accordingto an embodiment of the present invention using a pressure driven flowprofile to affect separation of components in a sample;

[0030]FIG. 8b is a side view of a component concentrator that uses anelectrophoretic flow profile and component retaining electrodes disposedtransversely with respect to the direction of electrophoretic flow;

[0031]FIG. 9 is a top view of an analytical device including a pressuregenerator and frangible seals according to yet another embodiment of thepresent invention;

[0032] FIGS. 10-13 are top views of various exemplary analytical devicesaccording to embodiments of the present invention;

[0033]FIGS. 14a and 14 b are a side view and top view, respectively, ofan analytical device according to yet another embodiment of the presentinvention;

[0034]FIGS. 15a, 15 b, and 16 depict various systems used in connectionwith the Examples described below;

[0035]FIG. 17 is a schematic illustration of an apparatus according toan embodiment of the present invention including an enlarged portionshowing a tip of an epoxy-coated electrode;

[0036]FIG. 18 is a schematic drawing illustrating a modified electrodeuseful in accordance with embodiments of the present invention;

[0037]FIG. 19 is a schematic illustration of an apparatus according toyet another embodiment of the present invention; and

[0038]FIG. 20 is a schematic illustration of an electrophoretic deviceaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0039] The bubble-free electrodes of the present invention can include avariety of designs and compositions. Different materials and designs canbe used to obtain the bubble-free electrodes of the present invention,including different chemical compounds and combinations of compounds. Anexample of a bubble-free electrode useful in accordance with the presentinvention is a palladium metal anode.

[0040] Palladium metal anodes are particularly useful in accordance withan embodiment of the present invention. When palladium is used as acathode under conditions that result in the electrolysis of water, thepalladium is able to store hydrogen generated by the cathode byabsorbing the hydrogen in the interstices of the palladium lattice. Inmetal electrodes that do not include palladium, hydrogen is not absorbedby the metal but rather leads to the production of hydrogen gas bubblesat the electrode surface. According to embodiments of the presentinvention, palladium anodes are provided that include stored hydrogenuseful in preventing the formation of oxygen bubbles at the anode duringoperation of a cell including the anode.

[0041] The capacity to store hydrogen is strongly influenced by thetemperature of the anode, the rate at which hydrogen is generated, themorphology of the palladium surface, and the crystal grain size of thepalladium. Guidance for enabling those skilled in the art to optimizeparameters and resulting electrode characteristics is provided by theexemplary electrodes, devices, and Examples set forth herein. Once thehydrogen-storing capacity is exceeded, the palladium anode will generatehydrogen bubbles unless something is done to deplete the electrode ofstored hydrogen. The anode can be prepared with hydrogen by reversingthe polarity in this same step to render it a cathode, andsimultaneously the cathode can be run as an anode and depleted ofhydrogen in preparation for the next cycle.

[0042] According to embodiments of the present invention wherein anelectrochemical cell is provided and the cell anode is pre-charged underreverse polarity conditions to store hydrogen, the amount of time foroperating the electrode under pre-charging conditions can depend uponthe current and voltage provided by the power supply. A sufficientamount of pre-charging time can be an amount of time under which theanode attains at least about 1% or greater of its hydrogen absorptioncapacity, for example, greater than 50% of its hydrogen absorptioncapacity, greater than 90% of its hydrogen absorption capacity, or toabout the full hydrogen absorption and storage capacity of theelectrode.

[0043] Although the palladium metal material and other electrodematerials used according to an embodiment of the present invention maynot store oxygen gas, when a cell including the material is operatedunder normal anodic operating conditions following pre-charging, theformation of oxygen gas bubbles at or due to the electrode are preventedor reduced. Instead of generating oxygen gas, the pre-charged palladiumor hydrogen-absorbing electrode, for example anode, of the presentinvention reacts with the reservoir of hydrogen stored in thepre-charged electrode material. As a result of pre-charging, the storedhydrogen is oxidized rather than generating oxygen gas.

[0044] According to an exemplary embodiment of a method and deviceaccording to the present invention, a first electrode, which operates asan anode under normal operating conditions, operates as an cathodeduring a reverse-polarity pre-charging preparation process. The firstelectrode can be pre-charged ex-situ, or pre-charged in-situ. Whenpre-charged in-situ, a device including the electrode can be operatedunder open or pre-sealed conditions so that bubbles generated by theelectrode operating as an anode during pre-charging can be vented to theatmosphere while hydrogen accumulates at the hydrogen-absorbingelectrode acting as a cathode during pre-charging. After a pre-chargingperiod of sufficient length to enable the electrode to store an adequateamount of hydrogen under the respective electrical conditions, the cellcan be sealed.

[0045] The cell can be pre-charged and then sealed or closed prior tonormal operation or during normal operation. Electrolysis can bediscontinued during sealing or closing the cell and the cell cansubsequently operate under normal conditions as a bubble-free electrodefor a period of time. According to an embodiment of the presentinvention, the sealed or closed cell can operate after pre-chargingunder conditions such that an electrode, previously pre-charged to storehydrogen, operates as a bubble-free anode.

[0046] The cell can be pre-charged while simultaneously venting oxygengas produced during the pre-charging process. After the preparation andventing, the device can be permanently sealed without the need to ventagain.

[0047] According to embodiments of the present invention, a device canbe created that includes an electrochemical cell that can operatebubble-free under normal electrolytic operation for extended periods oftime limited mainly by the volume of hydrogen stored at the electrodeand the ability of the cell to prevent oxygen bubble formation at thecell anode. According to embodiments of the present invention, a devicesuch as that shown in FIG. 9, having, for example, a 10 cm separationchannel, is provided that includes an electrochemical cell that canoperate bubble-free under normal electrolytic operation (i.e., undernormal polarity, not reverse polarity, conditions) for at least about 20minutes at a current of up to about 5 mA and a voltage of up to about 2kV (kilovolts).

[0048] According to an embodiment of the present invention, abubble-free anode electrode is provided that does not generate an oxygenbubble at the anode if the current density is held at 72 A/m² (amperesper square meter) for one second. This assumes that the solution hasbeen previously degassed and that bubble formation is readily nucleated.In determining a condition for bubble-free operation according to anembodiment of the present invention, an electrolysis of pure distilledwater on the surface of an infinite plane electrode was tested atstandard conditions including a temperature of 25° C. and a pressure of1 atm. It was assumed that as a result of the electrolysis, oxygenbubbles would be created on the electrode surface when the oxygenconcentration on that surface reaches a saturation value C_(s). Howquickly this happens depends on the electric current density j at whichthis electrode operates and on initial oxygen concentration C₀ dissolvedin the water. It was also assumed that oxygen is transported away fromthe electrode only by means of diffusion, and the oxygen diffusioncoefficient is D. The time For the oxygen concentration to reach thesaturation value at the surface of the electrode is given by thefollowing formula:

t=64×pF ²(C _(s) −C _(o))×D/j ²  (1)

[0049] where F is Faraday's constant and equals=96500 C/mol.

[0050] Formula (1) allows estimations for critical time as a function ofinitial oxygen concentration and current density. For oxygen C_(s)=1.3mM/L and D=2×10⁻⁵ cm²/s at T=25° C. Assuming that initial oxygenconcentration is 0.1×C_(s), one can calculate that t=5120/j². Thus, t=1second if j=72 A/m². As a reference, the current density in a 50 mmcapillary at a current of 10 mA is about 5000 A/m².

[0051] An electrochemical cell is also provided according to the presentinvention that includes a bubble-free palladium anode of suchspecifications. A sample separation device including such an electrodeis also provided by the present invention as is an electrophoreticdevice including such a palladium anode.

[0052] According to an embodiment of the present invention, a device foraffecting one or more properties of a component in a sample is providedthat includes a bubble-free electrode. The device can include apalladium electrode as the bubble-free electrode, or some otherelectrode material or combination of materials. An exemplary embodimentis a device including an electrochemical cell having an electrode systemthat includes Mg₂Ni, (RE)Ni₅ wherein RE is a rare earth element, LiNiO₂,V₂O₅, or mixtures, combinations, or combined uses thereof. Otherbubble-free cells and systems that can be used according to embodimentsof the present invention to form a field that affects a property of asample component include reversible electrodes such as those describedin U.S. Pat. No. 5,605,662, galvanic cells, RAM cells, nickel-cadmiumcells, AC voltage-powered electrodes, microfabricated cells and devices,and other bubble-free cells and electrode systems, and combinationsthereof.

[0053] According to embodiments of the present invention, anelectrochemical cell is provided that can operate bubble-free undervoltage conditions of at least about 3 volts, for example, at leastabout 5 volts. According to embodiments of the present invention, anelectrochemical cell is provided that can operate bubble-free undervoltage per length conditions of at least about 10 volts/cm, forexample, at least about 25 volts/cm. According to embodiments of thepresent invention, an electrochemical cell is provided that can operatebubble-free under voltage per length conditions of up to about 100volts/cm. According to embodiments of the present invention, anelectrochemical cell is provided that can operate bubble-free undervoltage conditions of up to about 200 volts/cm. For electrochemicalcells according to the present invention including hydrogen-absorbingelectrodes, the cells can operate bubble-free under these electricalconditions while under electrolytic conditions.

[0054] According to an embodiment of the present invention, a device foraffecting one or more properties of a component in a sample is providedthat includes a bubble-free electrode material other than palladium. Anexemplary embodiment is a device including an electrochemical cellhaving an electrode system that includes Mg₂Ni, (RE)Ni₅ wherein RE is arare earth element, LiNiO₂, V₂O₅, or mixtures, combinations, or combineduses thereof.

[0055] Other bubble-free electrode materials and systems that can beused according to embodiments of the present invention include RAM cellssuch as

[0056] MnO₂, MnOOH|H₂O, KOH|Zn, ZnO,

[0057] nickel-cadmium cells such as

[0058] Cd, CdO|KOH(20% aqueous)|Ni(OH)₄, Ni(OH)₂, Ni,

[0059] and others.

[0060] According to embodiments of the present invention, electrodematerials for bubble-free electrode operation in devices and methods ofthe present invention include electroplated iridium oxide electrodes.

[0061] According to embodiments of the present invention, electrodematerials for bubble-free electrode operation in devices and methods ofthe present invention include ionic conductors, polymer electrolytes,liquid electrolytes, gels, polyethylene oxide (PEO) materials, ceramicssuch as NASICON, NAFION membranes, and the like, and mixtures andcombinations thereof. The present invention also encompassescombinations of two or more of these electrode materials as bubble-freeelectrode materials. An example of such a combined material is a mixtureof Ni(OH)_(x) electrode material with NAFION, PEO materials, gels suchas polyacrylamides and gelatin, cross-linked gels, ionic liquidelectrolytes such as organic molten salts, or polymer electrolytes.Electrodes can be made from such mixed materials or such materials canbe used as, for instance, covering materials for electrodes as describedin U.S. Pat. Nos. 6,245,508; 6,129,828; and 5,849,486, which are hereinincorporated in their entireties by reference. Other electrode orelectrolytic materials useful according to embodiments of the presentinvention include ionic liquids, for example, those that behaveelectronically like salt melts. Exemplary useful liquids according to anembodiment of the present invention remain fluid over a temperaturerange of about 300° C., and/or have very low vapor pressure.Imidazole-based ionic liquids can be used, including those having theformula:

[0062] wherein R is a lower alkyl group of 20 carbon atoms or less, amethyl group, an ethyl group, a propyl group, a butyl group, or otherorganic groups containing about 20 or fewer carbon atoms. The ionicliquid can be a salt with PF₆ ⁻ as shown, or a salt with another anion.

[0063] In addition, other electrode materials and designs that can beused in accordance with embodiments of the present invention includethose electrodes and designs taught in concurrently filed U.S. patentapplication Ser. No. ______, to Bryning et al., entitled “Manipulationof Analytes Using Electric Fields” and designated attorney docket no.4727, which is incorporated herein in its entirety by reference.

[0064] Finely divided palladium and porous palladium are usefulbubble-free electrode materials. Methods of manufacturing using thesematerials can provide a wide range of advantages. By applying a paste toa substrate and annealing at temperatures of up to 800° C or higher, orby just drying the electrodes, the electrodes can be made on varioussubstrates including metals, glasses, plastics, and the like, dependingon the desired application.

[0065] Bubble-free electrodes according to embodiments of the presentinvention can be chemically stable at a pH of from about 7 to about 9,for example, at a pH of about 8. Preferably, the electrodes exhibit lowtoxicity and are easily formed.

[0066] According to embodiments of the present invention, an analyticaldevice is provided that includes an electrochemical cell and a samplecontainment device. The electrochemical cell includes at least an anodicreservoir, a cathodic reservoir, an electrical connection between theanodic reservoir and the cathodic reservoir, and at least a firstbubble-free electrode disposed within one of the anodic reservoir andthe cathodic reservoir. A second electrode is disposed within the otherreservoir and may also be a bubble-free electrode. A power source isprovided having a more positive terminal that is normally in electricalcontact with the first electrode, and a more negative terminal that isnormally in electrical contact with the second electrode. Theelectrochemical cell operates in an electrolytic mode and generates anelectrical field when the power source is turned on and the cell isoperating in a normal mode of operation. The analytical device furtherincludes a power source polarity-inverting device for switching thecontacts between the terminals of the power source and the first andsecond electrodes.

[0067] By reversing the polarity of the terminals, the cell can bereverse-charged such that one or more of the electrodes stores orcreates a bubble-preventing compound that prevents formation of bubblesat the electrode surface when the cell is run in the normal electrolyticmode of operation. The sample containment device includes a samplecontainment chamber having an opening for introducing a sample into thechamber. The opening can be positioned with respect to theelectrochemical cell such that an electrical field generated by theelectrochemical cell can influence at least one property, such asmobility, of at least one component of a sample disposed in the samplecontainment chamber.

[0068] Because the bubble-free electrodes of the present invention canbe embodied in self-contained devices such as card-type devices alreadypreloaded with reagents and separation medium, they are particularlyuseful in integrated disposable devices. More particularly, thebubble-free electrodes of the present invention can be embodied insealed devices such as card-type devices already preloaded with reagentsand separation medium, sealed to prevent evaporation, and containingonly, for example, a sample entrance port, where they are particularlyuseful in integrated disposable devices. The present invention alsoenables low-voltage bubble-free electrodes useful for capturing andmoving biomolecules. Another application of the present invention is inthe form of inexpensive, disposable, washable, or refreshable devicesused in high-throughput laboratories for sample preparation, sampleconcentration, sample purification, sample delivery, and in separationdevices and methods.

[0069] Another use according to the present invention is to concentratenegatively charged biomolecules or dye molecules on an electrode andenable plug release into a channel whereby a plug of concentratedbiomolecules can be released into a channel as a single plug or pulse.Another use is to demonstrate concentration and manipulation ofnegatively charged dyes in array-like formats as electrodes on planarsurfaces. Further examples of such devices are described in more detailbelow, such as the devices shown in, and described in connection with,FIGS. 10, 11, 12, 14, and 15.

[0070] According to yet another embodiment of the present invention, ananalytical device is provided that includes a flow pathway, a flowmanipulating cell adjacent the flow pathway, and a pressure reliefpathway. The flow manipulating cell includes a confined reservoir, anexit port in communication with the reservoir, and a pressure generatingelectrode in the reservoir. The pressure generating electrode generatesgas bubbles within the reservoir upon application of a controlled powersource for increasing pressure within the cell. The pressure reliefpathway is in communication with the flow pathway and is useful foraffecting a flow through the flow pathway. The pressure-generatingelectrode can be a palladium electrode, for example, a bubble-freepalladium anode of the present invention. The pressure-generatingelectrode can be a palladium anode that runs bubble-free for a timeperiod of at least one second when held at a current density of about 72A/m² in a previously degassed solution. The flow pathway can include anelectrophoretic separation channel. The exit port can include afrangible seal, for example, a heat-meltable seal that is incommunication with a heating element.

[0071] The present invention also provides methods of formingbubble-free electrodes and electrochemical cells, and analytical devicescontaining the same, methods of manipulating components of a sample inan electric field formed by one or more of the electrodes and/or cellsof the present invention, and methods of sample injection using apressure-generating electrode according to the present invention. Inaddition, the present invention relates to the use of bubble-freeelectrodes in sample preparation and clean-up applications, in detectionapplications such as described in U.S. Pat. No. 5,833,826, hereinreferred to as “electroflow” applications, in active programmableelectronics devices, in Alien Technology nanoblock circuit technology,in the devices described in U.S. Pat. No. 6,071,394, in self-containedcard devices for diagnostics applications, in sample preparationmethods, in traveling wave separation methods, in multi-step separationmethods, in synchronized cyclic capillary electrophoresis methods, andthe like.

[0072] Exemplary devices, systems, and methods which can be adaptedaccording to the present invention to employ the bubble-free electrodesand methods of using same according to the present invention includethose described in U.S. Pat. No. 6,129,828; U.S. Pat. No. 6,099,803; U.SPat. No. 6,071,394; U.S. Pat. No. 6,068,818; U.S. Pat. No. 5,965,452;U.S. Pat. No. 5,833,826; U.S. Pat. No. 5,632,957; U.S. Pat. No.5,605,662; U.S. Pat. No. 5,384,024; U.S. Pat. No. 5,240,576; U.S. Pat.No. 4,001,100; International Patent Publication No. WO 00/74850 A2;International Patent Publication No. WO 99/50480; International PatentPublication No. WO 99/14368; and International Patent Publication No. WO98/48084, all of which are incorporated herein in their entireties byreference.

[0073] The bubble-free electrodes of the present invention, methodsusing them, and systems employing them, can be used in a wide variety ofdevices that include one or more electrodes. For example, variousembodiments of the present invention can be utilized in the capillaryelectrophoresis microchips described by Krishnamoorthy et al. in thepublication Analysis of Sample Injection and Band-Broadening inCapillary Electrophoresis Microchips, from CFD Research Corporation ofHuntsville Ala.; in the microfluidic analytical devices described byBecker et al. in the publication Polymer microfabrication methods formicrofluidic analytical applications, Electrophoresis, vol. 21, pp.12-26 (2000); in the capillary electrophoresis microchips described byDolnik et al. in the publication Capillary electrophoresis on microchip,Electrophoresis, vol. 21, pp. 41-54 (2000); in the microfabricateddevices described by Huang et al. in the publication ElectricManipulation of Bioparticles and Macromolecules on MicrofabricatedElectrodes, Analytical Chemistry, vol. 2001, pp. 1549-1559 (2001); inthe micromachining techniques and devices described by Campaña et al. inthe publication Microfabrication of Capillary Electrophoresis SystemsUsing Micromachining Techniques, J. Micro. Sep. 10, pages 339-355(1998); in the microfabricated capillary electrophoresis channelsdescribed by Liu et al. in the publication Optimization of High-SpeedDNA Sequencing on Microfabricated Capillary Electrophoresis Channels,Analytical Chemistry, vol. 71, pp. 566-573 (1999); in the microfluidicsystems described by McDonald et al. in the publication Fabrication ofmicrofluidic systems in poly(dimethylsiloxane), Electrophoresis, vol.21, pp. 27-40 (2000); in the dielectrophoresis submicron bioparticleseparation devices and methods described by Morgan et al. in thepublication Separation of Submicron Bioparticles by Dielectrophoresis,Biophysical Journal, vol. 77, pp. 516-525 (1999); in DNA molecule 0transportation described by Morishima et al. in the publicationTranportation of DNA Molecule Utilizing the Conformational Transition inthe higher order structure of DNA, CCAB 97 published on the internet onFeb. 13, 1998; in the transmission imaging spectrographic andmicrofabricated channel systems described by Simpson et al. in thepublication A transmission imaging spectrograph and microfabricatedchannel system for DNA analysis, Electrophoresis, vol. 21, pp 135-149(2000); in the devices described by Soane et al. in U.S. Pat. No.5,126,022; in the microchip electrodynamic focusing device and methodsdescribed by Ramsey et al. in U.S. Pat. No. 5,858,187; in theelectrochemical detectors described by Mathies et al. in U.S. Pat. No.6,045,676; in the capillary electrophoretic separation systems describedby West et al. in U.S. Pat. No. 6,159,363; in the microfabricateddevices described by Chow et al in U.S. Pat. No. 6,174,675 B1; in themicrofabricated devices described by Simpson et al. in U.S. Pat. No.6,236,945 B1; in the microchip devices described by Waters et al. inMicrochip Device for Cell Lysis, Multiplex PCR Amplification, andElectrophoretic Sizing, Analytical Chemistry, vol. 70, pp. 158-162(1998); in the biological detection systems described by Cheng et al. inPCT International Publication Number WO 00/37163; in the microfabricatedcapillary electrophoresis chip described by Mathies et al. in PCTInternational Publication Number WO 00/42424; in the microfabricationdevices described by Bukshpan in PCT International Publication Number WO00/73780 A1; in the microlithographic arrays described in PCTInternational Publication Number WO 94/29707; in the sorting devicesdescribed by Austin in PCT International Publication Number WO 98/0893;in the electrophoresis chips described by Mathies et al. in PCTInternational Publication Number WO 98/09161; in the capillaryelectrophoretic separation systems described by West et al. in PCTInternational Publication Number WO 98/49549; in the microfabricationdevices described by Sosnovski et al. in PCT International PublicationNumber WO 99/29711; in the microfabrication devices described byOstergaard et al. in PCT International Publication Number WO 99/49319;in the microfabricated capillary array electrophoresis chips describedby Woolley et al. in Ultra-high speed DNA fragment separations usingmicrofabricated capillary array electrophoresis chips, Proceedings ofthe National Academy of Sciences, USA vol. 91, pp. 11348-11352 (1994);in the microfabricated devices described by Woolley et al. in FunctionalIntegration of PCR Amplification and Capillary Electrophoresis in aMicrofabricated DNA Analysis Device, Analytical Chemistry, vol. 68, pp.4081-4086 (1996); and in the capillary electrophoresis chips describedby Woolley et al. in Capillary Electrophoresis Chips with IntegratedElectrochemical Detection, Analytical Chemistry, vol. 70, pp. 684-688(1998). All of these patents and other publications are incorporatedherein in their entireties by reference.

[0074] Referring now to the drawing Figs., in the embodiment of thepresent invention shown in FIG. 1, palladium electrode 6 and palladiumelectrode 7 are connected to a DC voltage source 1 and placed in closedreservoirs 4 and 5, respectively. The electrode 6 operates as an anodeand the electrode 7 operates as a cathode under normal operatingconditions. The normally-operating anode 6 is pre-charged, for example,prior to insertion into reservoir 4, or in-situ by reversing the chargeon the electrode for a pre-charging period prior to normal operation.Pre-charging of the anode can be affected by exposure of the electrodeto a hydrogen-rich environment.

[0075] Four valves 2 a-2 d are used to fill the reservoirs 4 and 5 withreagent. A capillary tube 3 is inserted into the two reservoirs 4 and 5and filled with reagent. Because of the pre-charging of anode 6, thesystem produces no gas bubbles at anode 6 or at cathode under normaloperating electrolytic conditions. Because no gas bubbles are generatedduring normal operation of the system, the reservoirs and capillary areable to be a closed system. Such a closed system is highly tolerant ofdifferences in elevations of the two reservoirs since siphoning isprevented by the closed system.

[0076] An appropriate sample-filling feature such as one of those knownto those skilled in the art, can be incorporated into the system.Depending upon factors including the charge of the components to beseparated from a sample, sample injection can be configured at or nearan appropriate end of capillary tube 3.

[0077] In an embodiment of the present invention such as shown in FIGS.2a and 2 b, the system is configured as a microfabricated device 11including a T-injection feature. The device includes four electrodes 16a-16 d, at least one of which includes a bubble-free electrode of thepresent invention. Any suitable leads can be provided for the electrodes16 a-16 d, for example, protruding leads as shown. The device shown inFIGS. 2a and 2 b can include, for example, four palladiummaterial-containing electrodes. The electrodes are patterned into wells12, 13, 14, and 15. A channel 19 is provided between patterned wells 14and 15, along which electrophoretic separation of components of a samplecan occur upon appropriate application of charge to electrode pair 16 aand 16 b. The amount of charge can be any suitable charge, for example,charges conventionally used, and appropriate charges as taught by theexemplary embodiments of the present invention described herein. Asample injection channel 17 is provided between patterned wells 12 and13 and can carry a sample to be separated into electrophoreticseparation channel 19. T-injection of the sample from either of wells 12or 13 can be controlled by appropriate charge application to electrodepair 16 c and 16 d.

[0078] A sealing cover 18 can be used during operation of the devicewhen the bubble-free electrodes of the present invention are usedbecause no bubbles develop. Because the system can be a closed systemduring operation, no siphoning is required and evaporation can beeliminated or reduced. The device 11 can be loaded and then sealed, asshown, or provided with one or more access ports through the sealingcover 18. Access ports can be provided, for example, above or otherwiseadjacent any number of the patterned wells 12, 13, 14, and 15.

[0079] In yet another embodiment of this invention, a system isconfigured as depicted in FIG. 3. In this embodiment, a technique knownas “electroflow” as described in U.S. Pat. No. 5,833,826, is enabled.The system has four valves 31 a-31 d and palladium electrodes 32 and 33.An electric field is established within capillary tube 38 by electrodes39 and 33. Components separated in capillary tube 38 exit the tube atend 38′ and are further carried past a detection area in an electricfield formed between the electrodes 32 and 33. In the embodiment shown,electrode 33 operates as an anode under normal electrolytic operatingconditions.

[0080] The palladium electrodes 32 and 33 cause ions exiting thecapillary tube 38 to flow in a field consistent with the field in thecapillary tube 38. The present invention allows the electroflowelectrodes 32 and 33 to be positioned very close to the detectioncuvette 35. Thus, power supplies 36 and 37 can operate at lower voltagesand still provide a field equal to that in the capillary tube 38 in thearea viewed by a detector system. The detector system can include anexcitation laser (not shown) and a camera 34 for imaging and colorseparation. This configuration also provides a substantial advantageover previous designs in that no current has to pass through any ofvalves 31 a-31 d, and no voltage must pass through reagent contained inthe valve orifice. This closed system avoids siphoning from reservoir toreservoir or from load bar to reservoir.

[0081] The load bar 39 can be an array of recesses machined into aconductive, metal bar, electrode, for example, a platinum or stainlesssteel bar. The ends of separation capillaries can be placed in therecesses along with sample, buffer, or both. An appropriate sampleinjection technique can be incorporated into the system or samplereservoir 39′ of load bar 39 can be drawn into end 38″ of capillary tube38.

[0082] Another embodiment of this invention is exemplified in FIG. 4. Inthis configuration, heaters 41, controlled by heater controller 44,raise the temperature of the palladium electrodes 42 and 46 to increasethe hydrogen permeability of the palladium. Two reservoirs 47 a and 47 bare filled with a suitable conductive buffer through valves 43 a-43 d. Acapillary 45 is filled with the same or a different conductive buffer.Each reservoir 47 a and 47 b has a wet-side communication with itsrespective valves and capillary 45, and a dry side opposite therespective electrodes 46 and 42. Hydrogen not absorbed by negativeelectrode 42 permeates the negative electrode 42 and forms hydrogen gasthat is drawn away by a low pressure source or vacuum 51. A power supply49 is provided. Hydrogen gas is supplied by pump 48 to the positiveelectrode 46 through the dry side of reservoir 47 a where it permeatesthe electrode 46 and is believed to become oxidized such that itprevents the generation of oxygen bubbles. The principal advantage ofthis configuration is that there is no service cycle required topreliminarily charge the positive electrode with atomic hydrogen. Such aconfiguration can run continuously.

[0083] An appropriate sample injection feature can be incorporated intothe system. Depending upon factors including the charges of componentssought to be separated from a sample, sample injection can be configuredat or near an appropriate end of capillary tube 45.

[0084]FIG. 5 is a top view of a card type or card style device accordingto an exemplary embodiment of the present invention. The device can bemicrofabricated to a size as small as one mm long, or shorter.Alternatively, the device can be longer than 1 mm, such as 10 cm orlonger. The device includes a channel system 54, electrode pair 50 and50′, and electrodes 56, 57, 58, and 59. All the electrodes 50, 50′, 56,57, 58, and 59 can be bubble-free electrodes according to one or moreembodiments of the present invention. A sample can be loaded byinjection or other contact with the device at sample access hole 55. Thesample can be pre-loaded, followed by an optional sealing of the device,or provided with an opening for contacting a sample. Sealing the devicecan be accomplished using conventional methods, such as hermeticsealing.

[0085] Either or both electrodes of electrode pair 50 and 50′ can beused to concentrate an analyte flowing in an electrophoretic fieldbetween electrodes 56 and 57. AC voltage can be applied to electrodepair 50 and 50′ to cause bubble-free flow effects that canadvantageously be used to influence the flow and separation of samplecomponents. By using the different electrode pairs, different parametersof separation can be achieved, particularly when electrode pair 50 and50′ are supplied with AC voltage. The result is a tunable system thatcan be tuned to capture one or more very specific components orbiomolecules from a sample. A further description of some uses ofelectrode pair 50 and 50′ will be apparent to those of skill in the artwhen taken in conjunction with the description of FIG. 8 set forthbelow.

[0086]FIG. 5 also illustrates exemplary filters 53 and 53′ and filterlocations. Filters 53 and 53′ can include porous membranes, plasticfilters, gels, semipermeable membranes, anionic membranes, or othersuitable separation devices that preferably can physically separate orisolate one or more components of a sample, and combinations thereof.The positioning of filter 53 allows components to pass through thefilter. Components of a sample can be concentrated on or in filter 53′.

[0087]FIG. 6 is a side view of a matrix device according to an exemplaryembodiment of the present invention wherein reference numeral 64 depictsa cover plate or upper plate including access holes (not shown) andwhich is spaced from a substrate 62 which can be made, for example, of aglass or plastic material. Holes provided in substrate 62 are filledwith a plurality of preferably bubble-free electrodes 60 according tothe present invention. The holes in the substrate can be filled with anelectrode paste material, by deposition such as electrodeposition, orplug-type electrodes can be inserted into the holes as by pressing,pouring or melt forming of the electrode material.

[0088] The cover plate 64 and the substrate 62 are spaced from eachother by way of spacers 65, that can be made, for example, of anelastomeric and/or adhesive material. The spacer material can be inertin and to reagents, samples, and conditions used for an analyticaltechnique employing the device. The space between the cover plate 64 andthe substrate 62 defines a sample containment volume 66 that can besealed when bubble-free electrodes according to the present inventionare used for the electrodes 60.

[0089] Each electrode 60 is provided with a lead or connector 61 forconnection to a power source. Each electrode 60 can be powered by aseparate or independent power source or supply relative to the otherelectrodes 60, and the voltages to be applied to each electrode maydiffer to cause differential attraction and repulsion of analytes.Different voltages can be applied to the various electrodes atpredetermined times for predetermined time periods for the purpose ofmoving, separating, and or concentrating sample components, such asbiomolecules from a biological sample, to, from, at, or near specificones of the electrodes. By reversing the charge applied to one or morespecific electrodes, an opposite affinity for specific components can beachieved. For example, by applying an opposite charge, a biomoleculethat would be attracted to a specific electrode under positive chargeconditions would be repulsed by the electrode under negative chargeconditions. As such, desired manipulations of biomolecules can beachieved. This embodiment of the present invention can particularlyadvantageously be used in the microchip matrix devices described in U.S.Pat. No. 6,071,394. Devices according to the present invention can haveas many as 100 electrodes or more in a microfabricated arrangement.

[0090] Means such as a control unit can be provided to supply eachelectrode 60 with an independent power or voltage such that eachelectrode will provide different affinities to specific samplecomponents than provided by the other electrodes. By changing thevoltages applied to the various electrodes 60, by providing differentvoltages to each electrode, and/or by applying voltages to theelectrodes for specified or sufficient time periods, selectiveattraction and/or repulsion of specific sample components can beachieved. Furthermore, isolation and concentration of specific samplecomponents can be achieved based on known or tested affinities orrepulsions of such components to specific voltages. A more specific useof such a matrix device is shown in FIGS. 14a and 14 b of the appendeddrawings, which are described in more detail below.

[0091]FIG. 7 is a side view of closed capillary tube analytical deviceaccording to an exemplary embodiment of the present invention. Thedevice includes two bubble-free electrodes 70 spaced apart at oppositeends of a closed capillary tube 72 and provided with electrode leads orconnectors. The device illustrates a use of the bubble-free electrodesof the present invention in a capillary environment. The device can beused by supplying various voltages or alternating voltages to the twoelectrodes, and can separate, move, concentrate, or otherwise manipulatea sample or components of a sample disposed in the capillary. After asample is loaded into the capillary, as, for instance, by capillaryaction before the electrodes are placed in or on the capillary ends, thedevice can then be sealed by inserting or forming one or both of theelectrodes in the end or ends of the capillary. Because the electrodesare bubble-free electrodes according to the present invention, thedevice can be permanently sealed after the electrodes are placed orformed at the capillary ends. An electrode paste material, electrodeplug, or melt-molded electrode material, for example, can be used.

[0092] According to embodiments of the present invention wherein aplurality of such capillary devices can be arranged in an array orstructure 700 as shown in FIG. 7b, a substrate 701 having a plurality ofend-sealing electrodes 703 can be provided with each of the plurality ofelectrodes 703 being centered in a capillary receiving recess 705 formedin the substrate 701. The electrodes can be mounted or otherwise fixedor positioned on the substrate such that by aligning the capillary endsor guiding them with the capillary receiving recesses 701 formed in thesubstrate 701, the plurality of capillaries can be sealed and aplurality of sealed capillary devices according to the present inventioncan be formed simultaneously. For this use, pin-type or pin-shapedelectrodes are suitable and can be sealed, adhered, melted, crimped, orotherwise fixed in place in the capillary ends after insertion ordisposal of samples in the capillaries.

[0093]FIG. 8a is a side view of a concentrator device that can be used,for example, in the device of FIG. 5 wherein electrodes 73 and 74 ofFIG. 8a could be used as electrodes 50 and 50′ of FIG. 5. In FIG. 8a,opposing electrodes 73 and 74 are disposed on opposite sides of achannel 71. Channel 71 is defined, for example, by a tubular member.According to an embodiment of the present invention, alternating current(AC) can be applied to the opposing electrodes 73 and 74 to create afield between them that affects flow through the channel 71. As shown inFIG. 8a, trace 800 is the trace of molecules that are relatively slowermoving or slower responding in the electric field formed betweenelectrodes 73 and 74, i.e., 800 is the trace for molecules having a lowcharge to size ratio. Trace 802 is the trace of molecules that arerelatively faster moving or faster responding in the electric fieldformed between electrodes 73 and 74, i.e., 802 is the trace formolecules having a high charge to size ratio. By applying even low ACvoltage between electrodes 73 and 74, manipulation of chargedbiomolecules can be achieved as explained further below.

[0094] As shown in FIG. 8a, the hydrodynamic flow 75 of a flow throughchannel 71 is depicted. The hydrodynamic flow 75 is the profile of theeffective velocity or the “envelope” of the flow. The hydrodynamic flow75 has various vector components as illustrated by vectors 76 a-76 c. Asshown in FIG. 8a, the vector or flow in the center of the channel 71,represented as vector 76 c, is faster than the flow at the edges of thechannel 71 represented by vectors 76 a and 76 b, i.e., closer to thewalls of the channel-defining tubular member, hence, the longer vectorlength for vector 76 c. This phenomenon is referred to herein aspressure driven flow.

[0095] If a specific biomolecule moves slower in an electric field, itis more often moving in the faster moving vector of the fluid flow,i.e., closer to the center of the channel than the sides. If a specificbiomolecule moves faster in an electric field, it is more often movingin the slower moving vector of the fluid flow, i.e., closer to the sidesof the channel than the center of the channel. As is depicted in FIG.8a, the device of the present invention is tunable such that thefrequency of specific biomolecules flowing through channel 71 can bechanged or adjusted to selectively concentrate certain components of asample flowing through the channel 71. In so doing, positioning ofcertain biomolecules or steering certain molecules into relativelyfaster or slower vectors of the fluid flow can be achieved.

[0096] According to an embodiment of the present invention, DC voltagecan be supplied to electrodes at opposite ends of the tubularmember-defining channel 71, to cause electrophoretic separation of asample flowing through the channel. In the absence of a gel or sievingmedium, all charged components of the sample should flow through thechannel, for example, in the direction shown by the arrowheads on thetraces 800 and 802. However, if AC voltage is applied to opposingelectrodes such as electrodes 56 and 57 shown in FIG. 5 to form anelectrophoretic separation channel, some components of the sample movingbetween those electrodes will move faster between the opposingelectrodes 56 and 57, than others. Faster moving components such asfaster moving biomolecules can become attracted to the AC fieldelectrodes (e.g., 50 and 50′ in FIG. 5 or 73 and 74 in FIG. 8a), andunder certain conditions these faster moving components can becomecaptured by the AC field electrodes. Furthermore, in devices wherein asieving medium is provided in an electrophoretic separation channel, theadditional use of AC field-generating electrodes can provide acomprehensive device having multiple dimensions of separation.

[0097] Channel sizes for the device of FIG. 8a can vary depending uponthe intended use and size of the device. The channels can vary fromabout 1 micron to about 10 microns in width, for example. The distancebetween the AC field-generating electrodes 73 and 74 can vary to be anysuitable distance but can be from about 2 microns to many cm. Suitablevoltages to be applied to the AC field-generating electrodes 73 and 74can be from about 1000 volts/cm to about 10,000 volts/cm, for example.The frequency of the alternating current can be from about 0.1 Hz toabout 1 kHz, for example, from about 0.1 Hz to about 10 Hz. With highervoltages, lower frequencies can be used. An exemplary voltage supplyscheme entails supplying +/−5 volts to electrodes 73 and 74 at afrequency of about 1 Hz with a separation distance between theelectrodes of about 50 μm (micrometers).

[0098] The device of FIG. 8a, preferably when used in a device such asthat of FIG. 5, can be tunable to achieve specific and effectiveseparation of charged biomolecules and can be used to capture onlyspecific biomolecules of a sample. The device combines the separationattributes of fluid flow or pressure driven flow separation with ACfield separation effects.

[0099]FIG. 8b is a side view of a component concentrator that uses anelectrophoretic flow profile and component-retaining electrodes disposedtransversely with respect to the direction of electroosmotic orelectroendoosmotic flow. As shown in FIG. 8b, the electroendoosmoticflow 805 of a flow through channel 801 is depicted. Theelectroendoosmotic flow 805 is the profile of the effective velocity orthe “envelope” of the flow. The electroendoosmotic flow 805 has variousvector components as illustrated by vectors 806 a-806 c, however, unlikethe differing vectors on the pressure driven flow depicted in FIG. 8a,the various vectors 806 a-806 c are equivalent under electroendoosmoticflow conditions as depicted in FIG. 8b. As shown in FIG. 8a, the vectoror flow in the center of the channel 801, represented as vector 806 c,is equivalent to the flow at the edges of the channel 801 represented byvectors 806 a and 806 b, i.e., closer to the walls of thechannel-defining tubular member.

[0100] Electrodes 803 and 804 are placed opposing one another in adirection transverse to the electroendoosmotic flow through the channel801. If specific biomolecules 802 are charged and current is applied toelectrodes 803 and 804, the field resulting between opposing electrodes803 and 804 will cause the biomolecules 802 to be drawn-to, held, andconcentrated at at least one of the electrodes, electrode 804 in theembodiment shown. Non-charged components will pass through channel 801while a charged component of interest can accumulate on an appropriateelectrode, 803 or 804.

[0101] As is depicted in FIG. 8b, the device of the present invention istunable such that the frequency of specific biomolecules flowing throughchannel 801 can be changed or adjusted to selectively concentratecertain components of a sample flowing through the channel 801. In sodoing, accumulating or concentrating certain biomolecules at electrodes803 and 804 in the channel can be achieved.

[0102] According to an embodiment of the present invention, DC voltagecan be supplied to electrodes at opposite ends of the tubularmember-defining channel 801, to cause electrophoretic separation of asample flowing through the channel. In the absence of a gel or sievingmedium, all charged components of the sample should flow through thechannel at equal rates. However, if AC voltage is applied to opposingelectrodes such as electrodes 56 and 57 shown in FIG. 5 to form anelectrophoretic separation channel, some components of the sample movingbetween those electrodes will move faster between the electrodes thanothers. Faster moving components, such as faster moving biomolecules,can become attracted to the AC field electrodes (e.g., 50 and 50′ inFIG. 5 or 803 and 804 in FIG. 8b), and under certain conditions thesefaster moving components can become captured by the AC field electrodes.Furthermore, in devices wherein a sieving medium is provided in anelectrophoretic separation channel, the additional use of ACfield-generating electrodes can provide a comprehensive device havingmultiple dimensions of separation.

[0103] Channel sizes for the device of FIG. 8b can vary depending uponthe intended use and size of the device. The channels can vary fromabout 1 micron to about 10 microns in width, for example. The distancebetween the AC field-generating electrodes 803 and 804 can vary to beany suitable distance but can be from about 2 microns to many cm.Suitable voltages to be applied to the AC field-generating electrodes803 and 804 can be from about 1000 volts/cm to about 10,000 volts/cm,for example. The frequency of the alternating current can be from about0.1 Hz to about 1 kHz, for example, from about 0.1 Hz to about 10 Hz.With higher voltages, lower frequencies can be used. An exemplaryvoltage supply scheme entails supplying +/−5 volts to electrodes 803 and804 at a frequency of about 1 Hz with a separation distance between theelectrodes of about 50 μm (micrometers).

[0104] The device of FIG. 8b, preferably when used in a device such asthat of FIG. 5, can be tunable to achieve specific and effectiveseparation of charged biomolecules and can be used to capture onlyspecific biomolecules of a sample. The device combines the separationattributes of fluid flow or pressure driven flow separation with ACfield separation effects.

[0105]FIG. 9 is a top view of an analytical device 69 according to yetanother embodiment of the present invention. The device includes a PCRreaction and sample chamber 77, seals 78, 80, and 824, a reagentcontainer 79, a pressure generator 81, a low voltage conduit 82, achannel for electrophoretic separation 83, buffer containers 84, 86, and87, low voltage conduits 85, 813, 814, 816, 818, 820, and 822, and ahigh voltage conduit 85′, and buffer containers 86 and 87.

[0106] The pressure generator generates pressure, as for example, byincluding at least one gas-generating electrode and conditions thatenable gas generation. An exemplary system would be a gas-generatingpalladium electrode that has not been pre-charged according to thepresent invention, and run under conditions as a anode, generatingoxygen gas. Other gas-generating electrode systems could be employed,including platinum electrodes, other gas-generating metals, otherconducting gas-generating materials, semiconductors, and the like. Thecontainer portion of pressure generator 81 can also include appropriatebuffer or other material needed to cause gas-generation, such as anionic solution. Other generated gases can similarly be used to causesample injection, such as hydrogen gas, chlorine gas, carbon dioxidegas, and the like.

[0107] The generation of gas by the pressure generator can be timed withthe activation of current to lead or low voltage conduit 820.Application of current to conduit 820 is useful for breaking the seal 80that is made of a frangible material, for example, a heat-meltablematerial. The seal 80, as well as seals 78 and 824, can include, forexample, a paraffin wax material, polyethylene, polypropylene, styrene,plexiglass, or any suitable meltable plastic material or thermoplasticmaterial. The seal can be made integral with the material of chip 69such as formed as part of the channel 830 in the case of seals 78 and80. Upon melting of seals 80 and 78 by application of current toconduits 818 and 820, respectively, pressure generated from pressuregenerator 81 can flow through channel 830, forcing reagent from reagentcontainer 79 to flow further down channel 830 past broken or melted seal78 and cause sample from sample container 77 to be forced throughchannel 834. Upon application of current through conduit 816 to meltseal 824, the sample can be T-injected into channel 83 forelectrophoretic separation therein. Sample flowing from container 77continues to buffer container 86 which can be vented (not shown). Buffercontainers 84 and 87, at opposite ends of electrophoretic channel 83,can be vented but may not need vents if bubble-free electrodes accordingto embodiments of the present invention are employed. Conduit 85′ can bethe only high voltage conduit.

[0108] Conduits 816, 818, and 820 can be very narrow or made of highlyresistive material and sufficiently charged to locally heat therespective seals and cause them to melt, or to cause opening ofvalve-type re-closable seals. An appropriate power supply for the lowvoltage conduits would be a supply capable of providing from about 1.5to about 30 volts, for example, from about 5 to about 12 volts or fromabout 5 to about 6 volts. The high-voltage supply can supply from about100 to about 10,000 volts, for example, from about 1000 to about 3000volts.

[0109] The device shown in FIG. 9 is an exemplary microchip-type devicethat can be used to inject extremely small amount of sample into aseparation channel, and the device can inject extremely small andprecise amounts of appropriate reagents and sample as are required whenworking with nanoliter-sized volumes. The device can be microfabricatedand can be made to be 10 mm long or shorter with appropriate lowervoltage use, or as large as 10 cm long or longer. The device can befilled with appropriate reagents and buffers before sealing. Sample canbe introduced before sealing, or the device can be provided with asample injection port at container 77. The channels can be etched ormolded or punched, and the seals can be inserted, deposited or otherwiseformed in place. The substrate for the chip can be made of a glass orplastic material, or the like. The voltage conduits can be laid, welded,electrodeposited, or otherwise deposited.

[0110] FIGS. 10-13 are top views of various exemplary analytical devicesaccording to embodiments of the present invention that benefit from thebubble-free electrodes of the present invention. In FIGS. 10-13,Ni(OH)_(x) electrodes 89 are employed adjacent or within channels 88 andaccess ports 90 are provided for the channels. FIG. 10 depicts a simple,high voltage bubble-free chip device. FIG. 11 depicts a device thatemploys the separation technique described with respect to FIG. 8. FIG.12 depicts an exemplary T-injection device for liquid handling whereinsample injection is immediately adjacent an electrode at an end of anelectrophoretic separation channel. FIG. 13 depicts an alternative tothe FIG. 12 embodiment wherein a large sample access port is providedsuch that no filling vent is required in the device. Sample iselectrophoretically transferred through sample injection channel 88′until it reaches and is injected into separation channel 88. In each ofthe devices of FIGS. 10-13, appropriate leads or electrical connectorsare provided for each electrode. In the devices shown in FIGS. 10-12,either access port 90 can be used as a vent for filling sample into theother access port 90.

[0111]FIGS. 14a and 14 b are a side view and top view, respectively, ofan analytical device according to yet another embodiment of the presentinvention similar to the embodiment shown in FIG. 6. In FIGS. 14a and 14b, array-like devices with Ni(OH)_(x) electrodes are provided. Theelectrodes 95 are formed on or in a substrate 93 and wires 96 areconnected to respective electrodes with silver paste 94. A gasket 92separates a cover glass 91 from the electrodes 95. Access holes 90 areprovided in the cover glass 91. An exemplary length 97 of such a devicecould be about 2 cm.

[0112]FIGS. 15a, 15 b, and 16 depict various systems used to test thebubble-free and gas-generating electrodes of, and used in connectionwith, present invention. In FIG. 15a, in connection with the Examplesdescribed below.

EXAMPLES

[0113] Bulk Porous Electrode Experiment

[0114] A device as shown in FIGS. 15a and 15 b was used in thisexperiment to allow large volumes of generated oxygen to be released tothe atmosphere. The device is a practical device useful for testing thecapacitance of palladium electrodes to last without generating bubbles.The device can compare palladium electrodes to platinum electrodes. FIG.15a is a side view of the testing device and FIG. 15b is a bottom viewof the same device. The device includes platinum wires 200, pipette tips202 open at their upper ends, microscopic slides 204 and 205, a porouspalladium electrode 206, a rubber gasket 208, access holes 210 in slide204, and a buffer 212. The cell containing the electrode had dimensionsof 15×15×1 mm. Two access holes were drilled in the upper glass forconnecting the cell to two pipette tips with platinum wires connected inparallel and serving as the opposite electrode. The tested electrode wasmade from nanoporous palladium, grain size 30 nm, specific density 5.424g/cm³ (45% Pd), size 1×1.5×8 mm. At the start, all reservoirs orcontainers were filled with the same buffer material. The Pd electrodewas immersed in the buffer 1.5 mm deep. The volume of Pd exposed to thebuffer was 2.25 mm³. Using Faraday's law, as is known to those skilledin the art, the amount of gas generated by the platinum electrode andabsorbed by the palladium electrode of the present invention can becalculated.

[0115] Fresh Electrode Run:

[0116] A buffer comprising 10 mM Tris HCl mixed with 1 mM EDTA was usedand had a pH of about 8.0. The applied power was a voltage of 100V, aninitial current of 3 mA, and a final current of 0.5 mA. No bubblesformed for 50 minutes, and the total charge that passed was about 5C(equivalent to 0.55 ml of H₂). The polarity was then reversed, and thecell was run at an initial current of 0.5 mA, and a final current of 0.9mA, whereby no O₂ bubbles formed for 35 minutes.

[0117] Repeated Runs:

[0118] A buffer was provided and comprised a H₂SO₄ 1:100 dilution. Acurrent of 4 mA was applied and the anode ran bubble-free for 5 minutes.With an applied current of 2.3 mA, the anode ran bubble-free for 10minutes. The charge that passed was ˜1.2C (0.14 ml H₂).

[0119] After a few repeated runs, some cracks were observed in the partof the electrode that is exposed to the buffer because of differentexpansion of the immersed and non-immersed part of the electrode. Thestorage or diffusion of H₂ was negatively affected by the cracks athigher currents. Some bubbles were observed at sharp edges of the cracksbefore the electrode had reached full capacitance.

[0120] Thin Film Electrodes.

[0121] Thin Cu wires were soldered to one end of the electrodes. Theexposed part of the wire and the solder were coated with epoxy toprevent contact with buffer. For measurements the electrodes wereimmersed in a buffer in a small Petri dish. The buffer included 10 mMTris HCl mixed with 1 mM EDTA, and had a pH of about 8.0. Appliedvoltages, currents, and time to formation of H₂ were monitored.

[0122] Formation of bubbles was observed under a microscope.

[0123] Three types of electrodes were tested:

[0124] (1) thin film nanoporous Pd 20 μm thick (11×6 mm) baked at 600°C. on Al₂O₃ substrate;

[0125] (2) thin film nanoporous Pd 40 μm thick (5.5×10 mm) film dried at100° C., on Al₂O₃ substrate; and

[0126] (3) solid palladium foil 250 μm thick used in U.S. Pat. No.5,833,826. The foil was coated with epoxy and only one side dimensioned14×4 mm was exposed to the buffer.

[0127] The conditions for the first electrode were as follows: appliedvoltage 4 V, current 1.1 mA, time to first bubbles 20 min, total chargepassed 1.3 C. Reversed polarity, current 1.4 mA no O₂ bubbles for 15minutes.

[0128] The conditions for the second electrode were as follows: appliedvoltage 20V, current 10 mA, time to first bubbles 5 min, total charge3C.

[0129] The bubbles in both cases were formed at the edges were theelectric current was strongest. For different electrode arrangement, thetotal charge could be higher.

[0130] The conditions for the third electrode were as follows. Theapplied voltage was 4V, the applied current was 1 mA, the time untilfirst bubble formation was 100 min, and the total charge that passed was6 C. At an applied voltage of 15V, an applied current of 11 mA, for atime period of 30 min, the total charge that passed was 19.8 C. Underreverse polarity conditions, the applied voltage was 10 V, the appliedcurrent was 6.2 mA, and the time period was for 12 min.

[0131] Summary of the Charges Passed for the Tested Pd Electrodes Chargeper mm³ Exposed surface Total Material under exposed area area volumenanoporous Pd bulk 2.2 C  9 mm² 5.5 mm³ nanoporous film #1   1 C 66 mm²1.3 mm³ nanoporous film #2 1.4 C 55 mm² 2.2 mm³ solid Pd l.4 C 56 mm² 25 mm³

[0132] Nickel Hydroxide Electrodes

[0133] Nickel hydroxides is use in rechargeable alkaline batteries.Unlike Pd electrodes nickel hydroxides electrodes react with H⁺ and OH⁻ions without generating bubbles of H₂ or O₂ according to the formulae:

Ni(OH)₂(s)+2OH⁻⇄Ni(OH)₄(s)+2e⁻ and

Ni(OH)₄(s)+2H⁺⇄Ni(OH)₂(s)+2H₂O−2e⁻

[0134] where: (s)—solid, e⁻—electron

[0135] The electrode on one side should be connected to an electronicconductor (metal) and parameters like geometry, current densities, grainsize, packing density, electronic conductivity of electrodes, crack,etc. play important roles in optimizing the system. However, therelatively low currents used in electrophoresis of biomolecules works toan advantage.

[0136] Nickel Hydroxide Electrodes Experiment.

[0137] Two short glass tubes I.D. 1.5 mm, 10 mm long were packed withmixture of Ni(OH)₂ and Ni(OH)₄ from partially charged Ni—Cd battery. Onone side, Pt wires were inserted 3 mm inside the mixture and the sidewas sealed with epoxy. The short tubes then were put on the ends ofthinner glass tubes O.D 1.2 mm, I.D. 0.6 mm, 135 mm long filled with 50mM Tris buffer and the gap between them was sealed with epoxy. The twoopen ends of the longer tubes were placed in a vial filled with 50 nMTris buffer.

[0138]FIG. 16 shows a device for testing the length of time, asdetermined by visual inspection, before bubble formation under highvoltage conditions in a nickel hydroxide electrode system. The Pt wireswere connected to KEITHLEY electrometer and a high voltage potential of1000V DC was applied, as shown in FIG. 16. In the device of FIG. 16,reference numeral 215 depicts a KEITHLEY electrometer, 220 and 222depict electrodes, and 224 and 226 depict long tubes. The measuredcurrent equaled 275 μA. After 10 min, small bubbles on one electrodewere visible. The total charge passed equaled 0.165 C, which is only afraction of full theoretical capacity of the electrodes (˜10 C). It wasvisible that the packing of the nickel hydroxide was poor and there wasa short path to the Pt wires. To fix the problem a paste of finelypulverized nickel hydroxide is made with NAFION solution as a binder.The specific composition of the paste can be determined by therequirements of the specific application for which it is used.

[0139] In conclusion, the two selected materials for bubble-freeelectrodes worked as expected and together can be used to cover a widerange of applications. The palladium electrodes are more expensive butin solid or bulk nanoporous form can be incorporated in reusabledevices. Nanoporous palladium ink can be applied by printing on glass orplastics. Solid or baked at higher temperature palladium electrodes havehigh electronic conductivity and are advantageous in high-speedapplications like traveling wave separation. The connection to externalelectronics for the tested electrodes is relatively simple for the samereason.

[0140] Nickel hydroxide electrodes are inexpensive, can be easilymanufactured, and are useful in disposable devices. The electrodes areoptimized for use as cathodes or anodes.

Electroflow Example 1

[0141] Referring now to FIG. 17, an electroflow arrangement is shown forestablishing whether electrodes made of palladium would eliminate thevolume of hydrogen gas that would be generated during a sequencing runon the electroflow breadboard as described in U.S. Pat. No. 5,833,826.As previously mentioned, bubbles generated from electrolysis tend tocomplicate the fluid path and heat management aspects of electroflowbreadboards.

[0142] As seen in FIG. 17, the arrangement 100 includes negativeelectrode 102 and positive electrode 104 made of palladium tubing, andhaving outside diameters of 1 mm and 0.1 mm walls. The electrodes 102and 104 were immersed in tap water contained in a reservoir 106. Theimmersion depth of the electrodes was about 3 cm. An electrical system108 was used to supply a DC voltage of about 74 V to electrodes 102 and104 for electrolysis and the current noted was about 21 mA. Thearrangement was maintained at a temperature of approximately 21° C. Thetip of electrode 102 was crimped and provided with an epoxy insulator103. The role of the epoxy insulator was to minimize fieldconcentrations at the edge provided by the tip of the electrode 102 andminimize localized bubble formation.

[0143] After a period of approximately 12 minutes, bubbles appeared atthe negative palladium electrode. In order to remove the hydrogen fromthe negative electrode 102, the polarity of the electrodes was reversedfor approximately the same amount of time, that is, for approximately 12minutes. It was noted that oxygen gas did not appear at electrode 102,as a positive electrode, for approximately 12 minutes.

[0144] The above experiment was repeated three times with approximatelythe same results. A vacuum was applied to the negative electrode but noeffect was noted.

[0145] The above experiment led to the conclusion that at the notedtemperature, palladium absorbs a certain volume of hydrogen at thesurface only. The current noted in the above experiment, that is, 21 mA,was higher than the usual current for electroflow applications. However,with the assumption that electrolysis times of about 60 minutes orlonger will not be unusual in practice, the electroflow currentcorresponding to available flow cells and plumbing was calculated andverified on an experimental basis as being about 13 mA, as will bedescribed in further detail below. Future modifications can lower thevalue for current to approximately 9 mA, such as a slit height of 0.008inch. It is to be understood that the slit is a rectangular open sectionin the flow cell. By decreasing the height of the slit, the resistivesection of the conductive polymer is decreased, resulting in an increasein the effective resistance through the section. The resistance increaselowers the current for a given voltage as given in Ohm's law.

[0146] Considering Equation 1 below:

NαT×I  Equation 1

[0147] where:

[0148] N: the total number of hydrogen atoms absorbed;

[0149] T: run time of electrolysis in minutes;

[0150] I: applied current in mA,

[0151] what is expressed is that the total number of hydrogen atomsabsorbed is proportional to the run time of electrolysis in minutes,times the applied current in mA. In Example 1, I was equal to 21 mA andT was equal to 12 minutes. Therefore:

Nα12 min×21 mA  Equation 2

[0152] As previously stated, the electroflow current corresponding toavailable flow cells and plumbing was calculated and verified on anexperimental basis as being about 13 mA. Therefore:

Nα19.4 min×13 mA  Equation 3

[0153] In other words, one would have 19.4 minutes of bubble-free runtime in electrolysis with an electrode of the surface area used inElectroflow Example 1. Increasing the surface area of the electrodewould increase the bubble-free run time. The surface area of electrode102 would be: $\begin{matrix}{\begin{matrix}{A = {{immersion}\quad {depth} \times 2 \times {radius}\quad {of}\quad {electrode} \times \pi}} \\{= {{30\quad {mm} \times 2 \times 0.5\quad {mm} \times \pi} = {94.24\quad s\quad {q.\quad {mm}}}}}\end{matrix}\quad} & {{Equation}\quad 4}\end{matrix}$

[0154] Thus, for an area A of about 94.24 sq.mm, at about 13 mA, the runtime can go up to about 19.4 min without the appearance of hydrogen gas.Thus, for a run time of about 60 min, the area must be:

A=(60/19.4)×94.24 sq.mm=292.175 sq.mm  Equation 5

[0155] In view of the above, it can be concluded that an electrodehaving a surface area of approximately 300 sq.mm should work in thearrangement of FIG. 17.

[0156] Referring now to FIG. 18, a design for a modified electrode isshown in the form of electrode 102′. Here, the electrode 102′ includes asheet of palladium measuring about 12.5 mm by 12.5 mm, and having beeninsulated at edges thereof with an insulating border 103 bordering anexposed palladium surface 101.

[0157] According to one embodiment of the present invention, a set-upfor removing the hydrogen from the palladium surface can involve aspecial hydrogen removal electrode located close to the palladiumelectrode. This hydrogen removal electrode would be used only during the“cleaning” cycle of the electroflow arrangement. Close proximity wouldallow very high currents such as 1000 mA to be used at low voltages,such as 12 volts DC, over a proportionally short time, such as oneminute.

[0158] According to an alternative embodiment of the present invention,the preference of oxygen to react with hydrogen can be exploited.According to this embodiment, two palladium electrodes similar to theone described in FIG. 18 can be used. Prior to using the machine forsequencing, a reverse polarity would be applied to the electrodes. Thiswould saturate the normally positive electrode with hydrogen. During asequencing run, the electrode would be positive, and oxygen would thenreact preferentially with the hydrogen saturated electrode rather thanproduce oxygen bubbles. The negative palladium electrode would absorbthe hydrogen bubbles. At the end of the sequencing cycle, the polarityof the electrodes would again be reversed to “recharge” the electrodesprior to the next sequencing run. It is further possible to use apositive electrode having a surface area of only about one half of thesurface area of the negative electrode since only one atom of oxygen isproduced for every two atoms of hydrogen used. Possible benefits of theabove design include a bubble-free electroflow system, a very shortconductive path for electroflow resulting in substantially lowerelectroflow voltage, no weirs or associated valves, and potential costsavings and enhanced performance.

Electroflow Example 2

[0159] Referring now to FIG. 19, a modified version of the arrangementof FIG. 17 was used. Here, electrode 102 of FIG. 17 was replaced withelectrode 102′. Electrode 102′ was a flat sheet of palladium having beenplaced in the tap water at an immersion depth about 11 mm, and furtherhaving a width of about 22 mm. The capacity to absorb hydrogen being asurface phenomenon, very thin gage or material was used. The edges ofelectrode 102′ were coated with an insulating border made of epoxy inorder to minimize field concentrations at the edges of the electrode. Anelectrical system 108′ was used to supply a DC voltage of about 50 V toelectrodes 102′ and 104 for electrolysis and the current noted was about13 mA.

[0160] After a period of approximately 60 minutes, bubbles appeared atthe negative palladium electrode. In order to remove the hydrogen fromthe negative electrode 102′, the polarity of the electrodes was reversedfor approximately the same amount of time, that is, for approximately 60minutes. It was noted that oxygen gas did not appear at electrode 102′,acting as a positive electrode for the duration of the run.

[0161] According to one embodiment of the present invention, theprinciples demonstrated in Examples 1 and 2 can be put into practice. Inthis regard, reference is now made to FIG. 20, where an electrophoreticarrangement 111 according to an embodiment of the present invention isdepicted in schematic form. Here, a first electrode 112, a secondelectrode 114, and a third electrode 116, all made of palladium, areshown used in conjunction with an array of channels, such as, forexample, capillaries as shown at 124. The second electrode 114 and thirdelectrode 116 are placed in a cuvette 118 supplied with an electrolytesuch as a polymer, for example such as POP6 electrolyte or anothersuitable and/or conventional electrolyte. The electrolyte was suppliedthrough an inlet 122 and the polymer was capable of being dischargedthrough an outlet 120 as shown. The inlet 122 and outlet 120 wereprovided with respective valves 123 and 121 for controlling the flow ofpolymer into and out of the cuvette 118.

[0162] In operation, cuvette 118 was first filled with an electrolyticpolymer, and valves 121 and 123 were then closed. Then, the thirdelectrode 116 was set to be an anode, and the second electrode 114 wasset to be a cathode. The electrolysis was then run for a period of timeto charge the second electrode 114 to the extent desired. The period oftime of this first run corresponded approximately to the period of timethat the sequencing run was subsequently performed without generatingbubbles at the electrodes. During this first run, oxygen bubbles formedat the second electrode 114. Thereafter, the cuvette polymer was washedout with fresh polymer, and, after a sample injection, the firstelectrode 112 was set to be a cathode, the second electrode 114 was setto be an anode, and the third electrode 116 was set to be a cathode. Anelectrophoresis run was then advantageously made without the formationof bubbles at the second electrode, for the reasons described inrelation to Electroflow Examples 1 and 2 above. In this way, adisruption of the electrophoresis by bubbles was advantageouslyprevented.

[0163] The above Electroflow Examples according to the present inventionrepresent uses of the principles of the present invention in anelectrophoretic system similar to the system shown in U.S. Pat. No.5,833,826, the disclosure of which is incorporated herein in itsentirety by reference.

Comparative Examples Using Stainless Steel Electrodes

[0164] According to other Experiments, it has been found that, while theuse of stainless steel electrodes leads, after a very short time, to theformation of gas bubbles at those electrodes under conditions ofelectrolysis, the use of electrodes made of palladium, on the otherhand, prevents the formation of such gas bubbles for a much longerperiod of time. It is noted that the period of time during which apalladium electrode absorbs hydrogen atoms during electrolysis is, amongother things, dependent on its exposed surface area, that is, thesurface area available for electrolysis. The larger the exposed surfacearea of the electrode, the longer the period of time during which thepalladium electrode will prevent the formation of gas bubbles underconditions of electrolysis. Stainless steel electrodes, on the otherhand, lead to gas bubble formation in as short a time as 15 seconds.

[0165] It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments of thepresent invention without departing from the spirit or scope of thepresent invention. Thus, it is intended that the present invention coverother modifications and variations of this invention within the scope ofthe appended claims and their equivalents.

What is claimed is:
 1. An analytical device comprising anelectrochemical cell and a sample containment device, saidelectrochemical cell comprising: an anodic reservoir adapted to receivean electrolyte; a cathodic reservoir adapted to receive an electrolyte;a connection between said anodic reservoir and said cathodic reservoirfor permitting communication of electrolyte from at least one of saidreservoirs to the other of said reservoirs; a first bubble-freeelectrode disposed within one of said anodic reservoir and said cathodicreservoir; a second electrode disposed within the other of said anodicreservoir and said cathodic reservoir; a power source having a positiveterminal that is normally in electrical contact with said firstelectrode, and a negative terminal that is normally in electricalcontact with said second electrode, said electrochemical cell operatingin an electrolytic mode and generating an electrical field when saidpower source is turned on and said cell is operating in a normal mode ofoperation; and a power source polarity inverting device for switchingthe contacts between the terminals of said power source and said firstand second electrodes such that said negative terminal is in electricalcontact with said first electrode and said positive terminal is inelectrical contact with said second electrode; said sample containmentdevice comprising a sample containment chamber, said sample containmentchamber including an opening for introducing a sample into said chamberand being positioned with respect to said electrochemical cell such thatan electrical field generated by said electrochemical cell can influenceat least one property of at least one component of a sample disposed insaid sample containment chamber.
 2. The analytical device of claim 1,wherein said at least one property comprises the mobility of said atleast one component.
 3. The analytical device of claim 1, wherein saidat least one property comprises the rheology of said at least onecomponent.
 4. The analytical device of claim 1, wherein said at leastone property comprises the viscosity of said at least one component. 5.The analytical device of claim 1, wherein said second electrode is abubble-free electrode.
 6. The analytical device of claim 1, wherein atleast one of said first and second electrodes comprises a palladiummetal material.
 7. The analytical device of claim 1, wherein both ofsaid first and second electrodes comprise a palladium metal material. 8.The analytical device of claim 1, wherein at least one of said first andsecond electrodes comprises a nickel hydroxide material.
 9. Theanalytical device of claim 8, wherein said nickel hydroxide materialincludes a nickel hydroxide compound of the formula Ni(OH)_(x) wherein xis 2 or
 4. 10. The analytical device of claim 1, wherein both of saidfirst and second electrodes comprises a nickel hydroxide material. 11.The analytical device of claim 10, wherein said nickel hydroxidematerial includes a nickel hydroxide compound of the formula Ni(OH)_(x)wherein x is 2 or
 4. 12. The analytical device of claim 1, wherein atleast one of said first and second electrodes comprises a nickel-cadmiumelectrode system.
 13. The analytical device of claim 1, wherein at leastone of said first and second electrodes comprises an ionic liquid. 14.The analytical device of claim 1, wherein at least one of said first andsecond electrodes comprises an ionic conductor selected from liquidelectrolytes, gels, polymer electrolytes, ceramics, glasses, membranes,and combinations thereof.
 15. The analytical device of claim 1, whereinat least one of said first and second electrodes is connected said powersource and said power source comprises an alternating current powersupply.
 16. The analytical device of claim 1, wherein said samplecontainment device comprises an electrophoretic device.
 17. Theanalytical device of claim 1, wherein said sample containment devicecomprises an electroosmotic device.
 18. The analytical device of claim1, wherein said electrochemical cell operates in a galvanic mode whensaid power source polarity inverting device switches the contactsbetween the terminals.
 19. The analytical cell of claim 1, wherein saidpower source produces from greater than 5 volts to about 200 volts. 20.An electrochemical cell comprising: an anodic reservoir adapted toreceive an electrolyte; a cathodic reservoir adapted to receive anelectrolyte; an electrical connection between said anodic reservoir andsaid cathodic reservoir for permitting communication of electrolyte fromat least one of said reservoirs to the other of said reservoirs; a firstbubble-free hydrogen absorbing electrode disposed within one of saidanodic reservoirs and said cathodic reservoir; a second electrodedisposed within the other of said anodic reservoir and said cathodicreservoir; a power source having a positive terminal that is normally inelectrical contact with said first electrode, and a negative terminalthat is normally in electrical contact with said second electrode; and apower source polarity inverting device for switching the contactsbetween the terminals of said power source and said first and secondelectrodes such that said negative terminal is in electrical contactwith said first electrode and said positive terminal is in electricalcontact with said second electrode.
 21. The electrochemical cell ofclaim 20, wherein said second electrode is a bubble-free hydrogenabsorbing electrode.
 22. The electrochemical cell of claim 20, whereinat least one of said first and second electrodes comprises a palladiummetal material.
 23. The electrochemical cell of claim 20, wherein bothof said first and second electrodes comprise a palladium metal material.24. The electrochemical cell of claim 20, wherein at least one of saidfirst and second electrodes comprises a nickel hydroxide material. 25.The electrochemical cell of claim 24, wherein said nickel hydroxidematerial includes a nickel hydroxide compound of the formula Ni(OH)_(x)wherein x is either 2 or
 4. 26. The electrochemical cell of claim 20,wherein both of said first and second electrodes comprises a nickelhydroxide material.
 27. The electrochemical cell of claim 26, whereinsaid nickel hydroxide material includes a nickel hydroxide compound ofthe formula Ni(OH)_(x) wherein x is either 2 or
 4. 28. Theelectrochemical cell of claim 20, wherein at least one of said first andsecond electrodes comprises a nickel-cadmium electrode system.
 29. Theelectrochemical cell of claim 20, wherein at least one of said first andsecond electrodes comprises an ionic liquid.
 30. The electrochemicalcell of claim 20, wherein at least one of said first and secondelectrodes comprises an ionic conductor selected from liquidelectrolytes, gels, polymer electrolytes, ceramics, glasses, membranes,and combinations thereof.
 31. The electrochemical cell of claim 20,wherein at least one of said first and second electrodes comprises isconnected to an alternating current power supply.
 32. Theelectrochemical cell of claim 20, wherein said electrochemical celloperates in a galvanic mode when said power source polarity invertingdevice switches the contacts between the terminals.
 33. Theelectrochemical cell of claim 20, wherein said power source producesfrom greater than 5 volts to about 200 volts.
 34. An analytical devicecomprising the electrochemical cell of claim 20 and a sample containmentdevice.
 35. The analytical device of claim 34, wherein said samplecontainment device comprises an electrophoretic device.
 36. Theanalytical device of claim 34, wherein said sample containment devicecomprises an electroosmotic device.
 37. A method of separating at leastone component from one or more other components in a sample, said methodcomprising: providing the analytical device of claim 1; loading a samplehaving multiple components in the sample containment device of theanalytical device; and operating the electrochemical cell of theanalytical device to generate a field that affects separation of atleast one of the components of the sample from at least one othercomponent in the sample.
 38. A method of separating at least onecomponent from one or more other components in a sample containingmultiple components, said method comprising: providing anelectrochemical cell of claim 20; operating the electrochemical cell togenerate a field; and using the generated field to affect separation ofat least one of the components of the sample from at least one othercomponent in the sample.
 39. A method of influencing at least oneproperty of at least one component in a sample, said method comprising:providing the analytical device of claim 1; loading a sample having acomponent in the sample containment device of the analytical device; andoperating the electrochemical cell of the analytical device to generatea field that influences at least one property of the component of thesample.
 40. A method of influencing at least one property of at leastone component in a sample, said method comprising: providing anelectrochemical cell of claim 20; operating the electrochemical cell togenerate a field; and using the generated field to influence at leastone property of the component of the sample so as to manipulate thecomponent.
 41. A method of preparing a bubble-free electrode forbubble-free operation under electrolytic conditions, said methodcomprising: providing the analytical device of claim 1 wherein saidbubble-free electrode comprises a hydrogen-absorbing material; actuatingsaid power source polarity inverting device for switching the contactsbetween the terminals of said power source and said first and secondelectrodes such that said negative terminal is in electrical contactwith said first electrode and said positive terminal is in electricalcontact with said second electrode; pre-charging the bubble-freeelectrode by operating said electrochemical cell under conditions ofreverse polarity relative to normal operation of the cell, saidpre-charging being conducted under sufficient electrical conditions andfor a sufficient time to produce and store hydrogen at the electrodewhich operates as an anode under normal operating conditions of theelectrochemical cell; and subsequent to pre-charging, operating theelectrochemical cell in a normal mode of operation such that hydrogenstored at the anode reacts with oxygen gas formed at the anode undernormal operating conditions to thereby prevent or reduce formation ofoxygen gas bubbles at said anode.
 42. The method of claim 41, whereinsaid electrode that operates as an anode under normal operatingconditions comprises a palladium material.
 43. A device for separatingcomponents of a sample, comprising: a channel defined at least in partby one or more inner walls; a flow generating device for generating aflow of flow medium through said o channel; an electrode pair includingat least one electrode disposed at or adjacent said one or more innerwalls; a power supply for supplying said electrode pair with a powersupply of sufficient voltage and/or current to form an electric fieldthat extends between the electrode pair in a direction that istransverse to the direction of flow; and a controller for controllingsaid power supply to move charged components of said sample in adirection that is transverse to said direction of flow.
 44. The deviceof claim 43, wherein said flow generating device is an electrophoreticflow-generating device.
 45. The device of claim 43, wherein saidflow-generating device is a pressure-driven flow-generating device. 46.The device of claim 43, wherein said controller controls said powersupply so that at least one of said electrodes captures one or morecomponents from said flow.
 47. The device of claim 43, wherein at leastone electrode of said electrode pair is a bubble-free electrode.
 48. Thedevice of claim 43, wherein both electrodes of said electrode pair arebubble-free electrodes.
 49. The device of claim 43, further comprisingan electrophoretic field-generating pair of second electrodes whereinsaid second electrodes are disposed at or adjacent opposite ends of saidchannel, respectively.
 50. The device of claim 49, wherein at least oneof said second electrodes is a bubble-free electrode.
 51. The device ofclaim 49, wherein both of said second electrodes are bubble-freeelectrodes.
 52. A method of separating components of a sample,comprising: providing a channel at least partially defined by one ormore inner walls; causing a flow of flow medium through said channel ina direction of flow, said flow having a flow profile including regionsof faster flow and regions of slower flow; disposing a sample havingcomponents to be separated in said channel such that said sample iscarried by said flow medium in the direction of flow; providing anelectrode pair and disposing at least one electrode of said pair at oradjacent said one or more inner walls; supplying said electrode pairwith a power supply of sufficient voltage and/or current to form anelectric field that extends between the electrode pair in a directionthat is transverse to the direction of flow; and controlling said powersupply to move charged components of said sample in a direction that istransverse to said direction of flow to change the position of one ormore of said charged components in said flow from a region of a firstspeed to a region of a second speed that differs from said first speed.53. The method of claim 52, wherein said flow of flow medium is apressure-driven flow.
 54. The method of claim 52, wherein at least oneelectrode of said electrode pair is a bubble-free electrode.
 55. Themethod of claim 52, wherein both electrodes of said electrode pair arebubble-free electrodes.
 56. A method of separating components of asample, comprising: providing a channel at least partially defined byone or more inner walls; causing a flow of flow medium through saidchannel in a direction of flow, said flow having a uniformlycross-sectioned flow profile; disposing a sample having components to beseparated in said channel such that said sample is carried by said flowmedium in the direction of flow; providing an electrode pair anddisposing at least one electrode of said pair at or adjacent said one ormore inner walls; supplying said electrode pair with a power supply ofsufficient voltage and/or current to form an electric field that extendsbetween the electrode pair in a direction that is transverse to thedirection of flow; and controlling said power supply to move chargedcomponents of said sample in a direction that is transverse to saiddirection of flow, and to hold the position of one or more of saidcharged components in said flow to affect a concentrating of a chargedcomponent at an electrode.
 57. The method of claim 56, furthercomprising controlling said power supply to capture components at one orboth of the electrodes of said electrode pair.
 58. The method of claim57, further comprising releasing captured components from one or bothelectrodes of the electrode pair into the flow.
 59. The method of claim56, wherein said flow of flow medium is a pressure-driven flow.
 60. Asample separation device including an electrochemical cell, saidelectrochemical cell comprising an electrode that acts as an anodeduring normal operation of the cell, and an electrode that acts as acathode during normal operation of the cell, wherein, the cell has beenpre-charged such that the normally-operating anode has absorbed hydrogenand can run bubble-free for a period of time under normal electrolyticoperating conditions.
 61. The device of claim 60, wherein said electrodethat acts as an anode during normal operation of the device does notgenerate oxygen bubbles visible to the naked eye under conditions of acurrent density held at about 72 A/m² for about 1.0 second in a degassedsolution under conditions of ready-nucleation.
 62. A palladium anodethat does not generate oxygen bubbles visible to the naked eye underconditions of a current density held at 72 A/m² for one second in adegassed solution under conditions of ready-nucleation.
 63. Anelectrochemical cell including the palladium anode of claim
 62. 64. Asample separation device including the electrode of claim
 62. 65. Anelectrophoretic device including the palladium anode of claim
 62. 66. Ananalytical device comprising: a flow pathway; a flow manipulating celladjacent said flow pathway, said flow manipulating cell including aconfined reservoir, an exit port in communication with the reservoir,and a pressure generating electrode in said reservoir, said pressuregenerating electrode generating gas bubbles within said reservoir forincreasing pressure within the cell; and a pressure relief pathway incommunication with said flow pathway for affecting a flow through saidflow pathway.
 67. The analytical device of claim 66, wherein saidpressure-generating electrode is a palladium electrode.
 68. Theanalytical device of claim 66, wherein said pressure-generatingelectrode is a palladium anode that runs bubble-free for a time periodof at least about 1.0 second when held at a current density of about 72A/m² in a previously degassed solution under conditions ofready-nucleation.
 69. The analytical device of claim 66, wherein saidflow pathway includes an electrophoretic separation channel.
 70. Theanalytical device of claim 66, wherein said exit port includes afrangible seal.
 71. The analytical device of claim 70, wherein saidfrangible seal is heat-meltable and in communication with a heatingelement.